As a social activist and philanthropist, Thomas supports numerous charities, environmental initiatives and grass roots community organizations, including the Women's Earth Alliance, Global Green, the Jane Goodall Institute, Free the Slaves and MusiCares. In 2002 he founded the Common Ground Interfaith Forum in Philadelphia, to "support personal and social transformation, and build bridges of goodwill and understanding between people of different cultures and faith traditions." As Executive Director of Common Ground (2002–2008), Thomas established the Common Ground Choir, a performing ensemble of singers and musicians of diverse faiths and cultural backgrounds who celebrate a shared belief in the possibility of a less divided world.